Voltage problem

bryza · Post by **bryza** » 23 Mar 2022, 17:26

Hi Guys. I have a 2000 V70 that is not charging a new battery installed 3 weeks ago. Fully charged it reads 13.13 volts. A week later it reads 12.44 and won't start the car. Ironically the old battery sits at 12.74? When running the charge to the battery is 14.4 volts. Charge it for an hour and away you go. Charge from the alternator also reads 14.4 volts. Not sure where the regulator is to test but if 14.4 from the alternator it must be o.k? I have read that the positive leads can be a problem but would appreciate any advice going.

Cheers, Bryan.

Post by **abscate** » 23 Mar 2022, 17:53

Positive and negative cables need to be evaluated.

bryza · Post by **bryza** » 24 Mar 2022, 16:50

Thanks Abscate. Will give that a try. Cheers Bryza.

Post by **MrAl** » 11 Apr 2022, 09:21

Hello,

I agree with the cables inspection suggestion. Also the connections where the cables connect, including the ground and the alternator connection and the battery connectors themselves.

What happens sometimes when you have a bad connection is the alternator thinks the battery voltage is up high because it sees maybe the 14.4 volts, but due to the drop in the wire and/or connectors the battery really has much less voltage.

My old Hyundai had a problem with the ground on the alternator. The ground bolt had to be super tight just to get any charge at all. The ground is an important part of the circuit.

To test you can get a good digital volt meter and measure the voltage across the wires that go to the battery and from the metal case of the alternator to a ground near the battery. If you get more than 100mv drop when charging there is probably something wrong like a bad connection or wire.

Do get back here and let us know what was wrong if you find it.

Post by **misha** » 11 Apr 2022, 16:29

bryza wrote: ↑23 Mar 2022, 17:26 Hi Guys. I have a 2000 V70 that is not charging a new battery installed 3 weeks ago. Fully charged it reads 13.13 volts. A week later it reads 12.44 and won't start the car. Ironically the old battery sits at 12.74? When running the charge to the battery is 14.4 volts. Charge it for an hour and away you go. Charge from the alternator also reads 14.4 volts. Not sure where the regulator is to test but if 14.4 from the alternator it must be o.k? I have read that the positive leads can be a problem but would appreciate any advice going.

Cheers, Bryan.

Your digital multimeter battery ok?
If low battery warning is displayed on a digital multimeter...readings are all over the place and it can't be trusted.

Btw...12.7v state of charge is fully charged battery.